The principal objectives of the proposed research are (a) to investigate the dynamics and structure of the DNA-dependent RNA polymerase; (b) to resolve the complex processes of RNA synthesis into their elementary steps; and (c) to elucidate the regulatory mechanism of gene transcription. I propose to approach these objectives by a combined application of fast reaction techniques and fluorescence spectroscopy. Structural, kinetic, and thermodynamic information will be obtained in this way. The experimental approach involves: (1) the labeling of specific sites on RNA polymerase and DNA with spectroscopic probes; (2) the exploration of the microenvironments of these sites by fluorescence or EPR spectroscopy; (3) the kinetic studies of the interactions amongst RNA polymerase, DNA, nucleoside triphosphates, and RNA products using the chemical relaxation methods; (4) the systematic analysis of the molecular mechanism involved in the formation of the first and subsequent phosphodiester bonds; (5) the syncatalytic mapping of the selective sites and subunits during the course of RNA synthesis with energy transfer techniques; and (6) the elucidation of control mechanism by examining various factors affecting the elementary steps in the RNA polymerase reaction.